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Employee Benefit Plans - Weighted Average Asset Allocations by Asset Category (Detail) | Dec. 31, 2020 | Dec. 31, 2019
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Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items] |  |
Actual Asset Allocation as of December 31 (percentage) | 100.00% | 100.00%
Target Asset (percentage) | 100.00% |
Equity securities |  |
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items] |  |
Actual Asset Allocation as of December 31 (percentage) | 34.00% | 34.00%
Target Asset (percentage) | 32.00% |
Debt securities |  |
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items] |  |
Actual Asset Allocation as of December 31 (percentage) | 44.00% | 43.00%
Target Asset (percentage) | 49.00% |
Insurance (annuity) contracts |  |
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items] |  |
Actual Asset Allocation as of December 31 (percentage) | 12.00% | 12.00%
Target Asset (percentage) | 12.00% |
Real estate |  |
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items] |  |
Actual Asset Allocation as of December 31 (percentage) | 8.00% | 10.00%
Target Asset (percentage) | 4.00% |
Other |  |
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items] |  |
Actual Asset Allocation as of December 31 (percentage) | 2.00% | 1.00%
Target Asset (percentage) | 3.00% |

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- Definition Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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